Objective To intruduce a method of making cerebral perfusion mapping and measurement using dynamic CT with a personal computer. Methods We generated the cerebral perfusion mapping and measurement from a series dynamic CT images with a personal computer. The theoretic basis of our technique is central volume principle. The application software was made using visual C++ language with Windows 98 platform. Results This method was applied to a case of transient ischemic attack (TIA). The cerebral perfusion mapping contributed to display the abnormal area of ischemia, which showed as normal imaging appearances in routine CT and MR images. Conclusion Personal computer aided mapping and measurement of cerebral perfusion with dynamic CT is a simple and accessible technique for delineating the hemodynamic response, including abnormal regional cerebral blood flow, blood volume, mean transit time, and time to peak in cases of hyperacute ischemic stroke which was viewed as normal imaging findings in routine CT and MR examination. This method is more suitable to examine emergency cases than MR perfusion imaging and may be used in any facility where CT scanner and personal computer are available.

Objective To delineate the MR imaging features of intramedullary subependymoma. Methods The MR imaging features of 4 cases of pathologically proved intramedullary subependymomas were analyzed retrospectively and correlated with operative reports, and the differential diagnosis was discussed. Results MR appearances of intramedullary subependymoma were as follows: (1) Intramedullary subependymoma often involved the cervical region or the extensive portions of the cervical and thoracic cord in 3 out of 4 cases, mainly affected adults, and was eccentric within the spinal cord. The tumor was in the thoracic-lumbar cord in 1 case. (2) They were heterogeneously hypointense relative to the normal spinal cord on T 1-weighted images and hyperintense on T 2-weighted images, occasionally with hemorrhagic foci (2 cases). (3) No enhancement or minimal enhancement was revealed on T 1-weighted images following Gd-DTPA administration (3 out of 4). Conclusion Intramedullary subependymoma are best delineated by MR imaging. The diagnosis of intramedullary subependymoma should be considered when above findings are confronted.

Objective To investigate the applicative value in stages of pre-infarction period using dynamic perfusion CT. Methods Dynamic perfusion CT was performed in 32 cases of cerebral hypoperfusion. The ratios of side-to-side were measured at hypoperfusion areas in the regional cerebral ischemia. The stages of pre-infarction period were made as the following: (Ⅰ 1) TTP was delayed, MTT, rCBF and rCBV were normal; (Ⅰ 2) TTP and MTT were delayed, rCBF was normal, and rCBV was normal or slightly increased; (Ⅱ 1) TTP and MTT were delayed, rCBF was decreased, and rCBV was normal or slightly decreased; (Ⅱ 2) TTP and MTT were delayed, rCBF and rCBV were decreased. Results There were 4 cases in stage Ⅰ 1. Regional hypoperfusion was revealed only by TTP map. The mean ratios of rCBF, rCBV, MTT, and TTP were 1.00, 1.00, 1.00, and 1.30, respectively. In stage Ⅰ 2, the areas of delayed TTP and MTT were found in all 13 cases. The rCBF and rCBV maps appeared normal in 8 cases. Another 5 cases showed normal rCBF and slightly increased rCBV areas. The mean ratios of rCBF, rCBV, MTT, and TTP were 1.00, 1.03, 1.38, and 1.30, respectively. In stage Ⅱ 1, the areas of delayed TTP and MTT were revealed in all 8 cases. The depiction of decreased rCBF was also found in 8 cases. The areas of decreased rCBV were showed in 5 cases, and normal rCBV maps were revealed in 3. The mean ratios of rCBF, rCBV, MTT, and TTP were 0.56, 0.94, 1.49, and 1.47, respectively. In stage Ⅱ 2, the areas of delayed TTP and MTT were revealed in all 4 cases, in whom depiction of decreased rCBF and rCBV was also found. The mean ratios of rCBF, rCBV, MTT, and TTP were 0.42, 0.59, 1.57, and 1.55, respectively. Conclusion CT perfusion imaging and its parameters' analysis may play an increasing role to delineate the depiction of cerebral hypoperfusion in pre-infarction period. Analyzing the relationship of rCBF, rCBV, MTT, and TTP is very helpful to know the status of the capillary vessels in regional cerebral hypoperfusion area and to provide functional information with our stages of pre-infarction period.

Objective To preliminarily compare accuracy of magnetic resonance elastography (MRE) and T2WI in assessing stiffness of tissue.Methods Agar gel phantoms of 23 different concentrations ranging from 0.8％-3.0％ were produced.All the phantoms were examined with MRE and T2 map scanning respectively.After the raw images were processed by using local wavelength estimation (LEF),shear modulus of scan slice was measured,and T2 value of the same slice was measured with GE ADW4.3 workstation.Pearson correlation analysis was used to test the correlation between shear modulus and agar concentration,as well as T2 value and concentration.Rank sum test was used to compare the correlation coefficients of them.Results All the shear modulus and T2 values of the phantoms were successfully obtained,which were (49.1 ± 23.5) kPa and (57.8 ± 21.8) ms respectively.Shear modulus was positively correlated with concentration of agar gel(r1 =0.985,r1 2 =0.970,P ＜ 0.01),while T2 value was negatively correlated with concentration of agar gel (r2 =-0.901,r22 =0.812,P ＜ 0.01).The differences of these two correlation coefficients were statistically significant (Z =5.459,P ＜ 0.01).Conclusion MRE is more accurate to reflect stiffness of tissues relative to T2WI,and shows great clinical prospect.

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Objective 　To evaluate the clinical measurement of cerebral perfusion by dynamic CT. Methods　 Thirteen normal adults were examined by dynamic CT for the measurement of cerebral blood flow (CBF). Another dynamic CT scans with the measurement of CBF were performed separately to rule out cerebral ischemia in 5 cases and secondary Parkinson disease in 2. Results　 Normal cerebral cortical perfusion was measured at 59.3～96.8 ml*min-1*100g-1 with the　mean value 76.2 ml*min-1*100g-1. Normal white matter perfusion was measured at 27.1～43.1 ml*min-1*100g-1 with the mean value 33.9 ml*min-1*100g-1. In 5 cases of suspending cerebral ischemia, one showed increase of CBF and 4 presented decrease of CBF. In 2 cases of suspending secondary Parkinson disease, one appeared decrease of CBF and other one was normal. Conclusion　 Dynamic CT scan with the measurement of CBF can demonstrate the hemodynamic status of normal brain and pathological lesion. Combined with routine CT scan, measurement of cerebral perfusion by dynamic CT is an ideal method to show the morphological and functional changes of brain tissue simultaneously.

Objective To evaluate the role of diffusion weighted (DW) echo planar MRI in differentiating between brain abscesses and necrotic or cystic tumors. Methods Five patients with brain abscesses, 7 with malignant gliomas, and 1 with brain metastasis were consecutively examined using conventional MRI and diffusion weighted imaging (DWI). The apparent diffusion coefficient (ADC) of ROI was measured with two different b values (0 and 1 000 s/mm 2 or 0 and 1 200 s/mm 2). The results were analyzed using two independent samples test. Results On diffusion weighted imaging, brain abscesses showed marked hyperintensity in all 5 patients, whereas necrotic or cystic brain tumors demonstrated hypointensity in all 8 patients. ADC mean values of brain abscesses, which was 0.43?10 -3 cm 2/s, were lower than those of necrotic or cystic portion of brain tumors ( T =15.00, P

Objective To study the imaging findings of cerebral venous sinus occlusion and to improve the knowledge of this disease.Methods CT,MRI and DSA data in thirty six cases with cerebral venous sinous occlusion were retrospectively reviewed.There were 15 male and 21 female,ranged in age from 23 to 59 years old.Results On T_1WI and T_2WI,abnormal signals in cerebral parenchyma were found in 26 cases,of that there were brain hemorrhage with abnromal long T_1 and long T_2 signal in 16 cases,only abnromal long T_1 and long T_2 signal in 6 cases,cerebral ventrical enlargment in 4 cases and brain swelling in 4 cases.The abnormal venous enhancement was found in 25 cases on contrast-enhanced MRI.On CT scan,low density in cerebral parenchyma was found in 10 cases,it might be edema or ischemia,astime goes by,the density of cerebral venous sinus became slightly high density to isodensity.DSA showed dural sinus occlusion includingsuperior sagittal sinus in 15 cases,transverse sinus in 8 cases,sigmoid sinus in 7 cases,straight sinus in 4 cases and inferior sagittal sinus in 2 cases.Conclusion The venous sinus occlusive disease is distinctively different from arterial occlusive disease.CT and MR imaging is very important in diagnosing the cerebral venous sinus occlusive disease,but DSA is still the gold standard.

Objective To study the imaging characters of spinal teratomas.Methods 10 cases of spinal teratomas were analyzed with clinical and radiography. 8 cases intramedullary, 2 cases extramedullary. 10 cases had MR examination. Results The location of spinal teratomas in 5 cases was in lumbar, 3 cases in thorax, 1 case in thoracolumbar, 1 case in cervical. 7 cases were multicyst type, 3 cases were singlecyst type. 10 cases of MR image showed mix signal intensity. The contrast enhancement T 1WI with fat saturation presented disappear fat signal of spinal teratomas. The teratomas heterogeneous enhancement was found in 10 cases with MR examination. 3 cases lumbosacral area of spinal teratomas united tethercord. Conclusion Neuroradiological features of spinal teratomas has specific manifestation. The T 1WI fat saturation scan is a availability nicety method for spinal teratomas.